Method of forming sheet metal



F. H. STOLP.

METHOD OF FORMING SHEET METAL APPLiCATION FILED APR- 9, 1918- 1,408,232, Patented Feb. 28, 1922.

2 SHEETS-SHEET l.

INVENTOR 1 I I I MMMEFM F. H. STOLP.

METHOD OF ronmmc SHEET METAL.

APPLICATION FILED APR. 9, ma. Patented Feb. 28, 1922 2 SHEETS-SHEETZ.

60 HUM! Ill lHjE INVENTOR $5.85. flan/215520 Q "NH ATTORNEYS UNITED STA'l ES PAJENT oFFic ,MFRANK n. sronr, or GENEVA, NEW YORK.

METHOD OF FORMING SHEET METAL.

Specification of Letters Patent. Pate t d F b 2 1922.

Original application filed May 12, 1917, Serial No. 168,2 60. Divided and this application filed April 9,

, 1918. Serial No. 227,458.

To all who at it may cancer-n Be it known that I, FRANK H. Sronr, of (10mm, in the county of Ontario and State of New York, have invented certain new and useful Improvements in Methods of Forming Sheet Metal; and I do hereby declare the following tobe a full, clear, and exact de scription or" the same, reference being had to the accompanying drawings, forming a part of this specification, andto the reference-numerals marked thereon.

My present invention relates to metal working and more particularly to the forming oi sheet metal into tubes, moldings and the like, involving the bending or creasing of opposite lateral edges of a strip or blank and the invention has for its object to provide an improved method of this nature whereby a superior product of uniform quality and proportions, free, from malformations, may be produced rapidly and without distorting or straining the material worked upon. This application is a division of my prior application Serial No. 168,260, filed May 12, 1917 in which I claim an invention relating to machines through the medium of which this method of invention may be practiced and in describing the latter hereiml have found it convenient. to illustrate and describe the machine disclosed in said parent application as giving a clear idea of the mode of treating the material and of the results accomplished. To these and other ends the invention resides in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specification.

In the drawings:

Figure 1 is a si chine;

de elevation of the ma- Figure 2 is a top plan view of the machine;

Figure 3 is a horizontal sectional view of the machine the section being taken on the line 3 3 of Figure 1;

Figure lis a vertical cross section through the guide channel for guiding the mandrel of the machine, the section being taken on. the line 4e"-l of Figure :1;

Figure 5 is a side elevation of the outer end of the mandrel;

Figure 6 a vertical longitudinal section through the initial breaking die and folding plunger therefor, the section being taken on the line 6 6 of Figure 8;

Figure '7 is a vertical cross section through the breaking die and folding plunger, the section being taken on the line 7 7 of Figures 8 and 6.

F gures 8, 9, 10 and 11 are vertical cross sections through diiferent sections of the finishing dies for lock seaming the tube, the sections being taken on the "line 8"8*,

-9", 10-1O and li -11 respectively of Figure 3.

Similar reference numerals throughout the several views indicate the same parts.

The machine illustrated is designed for the production of lock seam tubing and the present invention will be described for convenience in connection with such an operation, though it will be understood and readily observed by those skilled in the art that other tubing, moldings and the like may be produced in a. similar manner.

The methods of making tubing hitherto practiced have usually involved a pull or draw on the metal which tends to make it porous and spongy and with. little life left in it. Also, it has been the practice to form the tubing in continuous lengths and to chop, shear or saw it at intervals where a quantity of short tubes is the product sought as, for instance, in the manufacture of automobile radiators and in such a ease,the sev-' ering operation not only reduces the speed of production but is almost sure to render the ends of the tubes rough or uneven and, generally, imperfect.

My present invention is applicable, particularly as carried out on the machine illustrated, to the production of such short length tubes with great rapidity and with a compressing rather than a stretching effect upon the sheet material used. The ends of the tubes are uniform and true and free from mutilation because identical with the edges of a prepared blank that may be sheared or otherwise formed while in a fiat state.

In practicing my invention, I prepare such a blank, usually of rectangular form with squared edges. I then preliminarily bend the blank (which in an automatic machine would be cut and delivered as required from a continuous roll or ribbon) at or near its center in a manner that maintains its ends parallel and brings its lateral edges parallel and toward each other. lVhile in such condition, I support the inner'surfaces of the blank against collapse beyond the inside diametrical limits of the tube desired and support the outside surfaces against expansion beyond the outside diametrical limits of the tube desired. While so held, I form the lateral edges inwardly toward the center with forming dies or otherwise, by an operation conducted progressively toward an end edge of the blank and at the same time, I resist the longitudinal thrust thereby created by pressure against the said end edge. The forming medium may move relatively to the blank while the said end edge rests against a fixed abutment, or a reverse action may be proceeded with whereby the blank is moved by a thrust against its end edge to carry its lateral edges progressively through the point at which the bending or creasing occurs so that, in any,event, the strain upon the blank is inwardly from each end in. the nature of a compression rather than a tensile strain tending to stretch or disrupt the metal. Being closely supportedon both sides, the metal cannot'escape submitting to this compression and as a result, the resistance at the creasing point is pro ressively overcome along its edges. The en s of the tube produced are therefore as perfect as the ends of the prepared blank and the tube is subjected to no lateral strains other than those 'con'ipletely borne by the supporting elements applied to the inner and outer surfaces of the blank. I prefer, where practicable, to push the supported blank vendwise past-"the creasing point.

The machine shown in the accompanying drawings for constructing tubing in accordance with the above method will give a better understanding of the invention and its benefits. Referring to the drawing, it comprises a bed plate 1 which forms a run way for the cross-head 2 to slide thereon. The bed plate 1 is supported by suitable legs 3 and 3' as shown in Figures 1 and 2. Bolted to the top of the bed plate atthe left hand end thereof is the channel frame 1 which is formed by the upright plates 5 and 6, which plates embrace the breaking and bending dies as hereinafter described.

The forming channel '15, into which the sheet metal plate is forced to conform to the outline thereof, comprises thelongitudinal bars 7 and 8 with the bar 9 supported between them. All of these barstogether with the upright plates 5 and 6 are rigidly held to ether by suitable bolts and form the chan nel frame 4 which in turn is fastened to the bed plate 1 as pointed out above.

The longitudinal bars 7. '8 and 9 form the sides and bottom of'the guide channello into which the-sheet metal plate is forced verti- 11 respectively.

cally by means of a plunger to form the bottom and sides of the tube. After this operation is completed, the sheet metal channel formed in this manner is pushed forward by means of a mandrel. On its forward movement with this mandrel, the sides of the sheet metal channel are folded over the top of the mandrel and the ends thereof are gradually locked into each otherby means Each of the longitudinal bars 7 and 8 is provided with anangular projection '10 and These projections extend upwardly between the upright plates 5 and 6 and form supports on each side of the guide channel 15 on top of which the sheet metal blanks are placed as shown at 12 in Figures 6 and 7.

Mounted to slide between the projections 10 and 11 is the plunger plate 13 which is carried on the outer en d of the arm lei. This arm is mounted to swing in the channel frame 4; and is pivotally mounted at the upper left-hand corncrthercof as shown in Figures 1 and 2. hen the plunger 13 is swung from the. dotted line position shown in Figure 1 'to the full line position shown in the same figure, the sheet metal plate 12,

placed on top of thesupports 10 and 11, as

shown in: Figure 6, is bent in the middle thereof and forced down betweenythe pr0 jections 10' and 11 and into the guide chan nel 15 as shown in full lines in Figure 7. The outline of the lower edge of the plunger 13 conforms to the outline of the bot-- tom of the guide channel 15 formed by the bar 9 so that the sheet metal plate 1 2- forced into this guide channel is bent into a channel having the same outline at the bottom thereof. V i

The sheet metal channel formed in this manner snugly adheres to the bottom and sides of the guide channel 15 due to the spring action of the sheet metal. This allows the plunger 13 to be withdrawn from the inside of the channel formed thereby leaving the sheet metal channel in place in the guide channel 15'. To withdraw the plunger plate 13 from within thechannel, the arm 14 is swung back from the full line position to the dotted line position shown in Figure 1. y

The reduced outer end. 16 ofthe mandrel 17 is then gradually inserted into the sheet metal tube formed by the plunger 13. This mandrel is supported at the right-hand end thereof by a ug 18 having an opening through the center thereof through which the end of the mandrel17 passes. Lock nuts 19 and 20 are provided on each side of the lug 18 and are threaded on the end of the mandrel 17 by means of which this end of the mandrel can be rigidly fastened to the lug 18 as shown in Figures 1 and 2. The lug 18 is carried on top of the crosshead and forms a part thereof. Tomove the forward end 16 and the mandrel 17 into the sheet metal channel previously formed by the plunger 13, the crosshead 2 is moved to the left on the bedplatc 1. As previously described, the outer end 16 of the mandrel 17 is of reduced diameter and is formed out of an upper section 21 and a lower section 22. The dividing line between these sections tapers towards the outer end of the mandrel so that the lower section 22, which is shorter than the upper section 21, can slide in and out thereon, it being: understood that the upper section 21 is integral with the mandrel 1 while the lower section 22 is made av separate member thereof. This is for a purpose that will presently appear.

The shoulder 23 formed on the inner end of the reduced end 16 of the mandrel 17 is adapted to engage the outer edge of the sheet metal channel on the. forward movement.

The outside diameter of the reduced end 16 equals the inside diameter of the sheet metal channel, while the outside diameter of the remainder of the mandrel 1? equals the outside diametcr of the sheet metal channel,

,which in turn equals the inside diameter of the guide channel 15. From this it will be seen that when the outer end of the mandrel has engaged the inside of the sheet metal channel, the sides of the mandrel beginning with the shoulder 23, form a continuation of the sides of the sheet metal channel and completely till the inside of the guide channel 15.

During the forward movement of the mandrel the sheet metal channel remains stationary in the guide channel 15 until the shoulder 23 engages the right-hand end of the sheet metal channel. In. order to prevent any accidental forward movement. of the sheet metal channel before the outer section 16 of the mandrel has completely filled the inside thereof and before the shoulder 23 has come in contact therewith a latch 24 is provided which projects into the inside of the channel frame 4: and across the path of the upper edge of the sheet metal channel as shown in Figure 7. This latch prevents the forward end of the sheet metal channel to move in the guide channel 15 beyond the projections 10 and 11 until the opposite end thereof has been engaged by the shoulder 23 of the mandrel 17 When the shoulder 23 has engaged the sheet metal channel on the forward movement of the mandrel, the latch 24 is lifted to allow the mandrel 16 to carry the sheet. metal channel with it and force it between the finishing dies as will presently appear. I

Mounted on top of the longitudinal bars 7 and 8 and overlapping the guide channel 15 are suitable finishing dies which gradually bend the upper portions of the sides of the sheet metal channel toward each other and also look the ends thereof together to convert the sheet metal channel into a tube. These finishing dies comprise several members which are illustrated in F igures 3, 8, 9, 10 and 11.

The member 25 which is mounted on top of the bar 7 partially overlaps theguide channel 15 and is shaped on the under side thereof to bend the upper portion of the right-hand side of the sheetmetal channel towards the left and over the top of the mandrel 16. The outer edge of this same side of the sheet metal channel is then bent back over the top of the member 25 by means of the member 26 as shown in Figure 8. At the same time the upper portion of the left ha-nd side of the sheet metal channel is bent towards the right and overthe top of the mandrel 16 by means of the member 27 which member is mounted on top of the bar 8 and overlaps the guide channel 15 from. the left.

The member 28 carried on the outside of the member 27 then gradually bends the outer edge of the lefthand side of the sheet metal channel over the edge of the outer end of the right-hand side of the sheet metal channel until the outer end of the left-hand side of the'sheet metal channel completely embraces the extreme outer end of the right hand side of the sheet metal channel as shown in Figures 9 and10.

After successively passing each of these members the finishing member 29 forces the joint thus made by the previous members down upon the top of the tube and partially into the groove 31 formed in the top of the upper section 21 of the mandrel 16.

The mandrel and sheet metal tube emerges, after passing underneath all of these members, from the left-hand side of the machine and moves out thereof until the whole of the sheet metal channel is formed into a tube. It will be understood that during the forward movement of the mandrel 16 the upper section 21 thereof has moved over the top of the lower section 22 until the diam eter of the combined mandrel was large enough to completely till out the inside of the tube which is gradually formed thereon, and when the mandrel 16 is withdrawn, the tube formed thereon is released therefrom as fol lows:

The upper section 21 on its rearward travel slides over the lower section 22 thereof until the pin 30 comes in contact therewith. This movement of the upper section 22 over the lower section 21 reduces the diameter of the mandrel 16 because of the inclined sur face of each of the sections. The reduction of the diameter of the'rnanorel in turn releases the inside ot the finished tube from the mandrel 1(5 and allows it to be taken ofif therefrom. litter the tube is released from the mandrel the pin 30- carries the lower section 22 with the upper section '21 to the rear and brings i into position for the forming of a new tube. lVhile the drawings show this machine adapted to form a hexagonal metal tube, it is understood that any other form such as a round or oval tube may be formed with the same machine by simply changing the outline of the bottom of the guide channel and using a mandrel having a cross section corresponding to the outline of the tube to be formed thereon.

I claim as my invention:- a

1. A method of forming tubing which con sists in bending a sheet metal blank to bring its lateral edges into closer proximity, supporting its inner surfaces against collapse beyond the inside diametrical limits of the tube desired, supporting the outside surfaces of the blank against expansion beyond the outside diametrical' limits of the tube desired, forming and interlocking the lateral edgesoit the blank by a longitudinal creasing operation conducted progressively toward an end edge of the blank While the latter is so 7 by a creasing operation conducted progressively toward an end edge of the strip and opposing the longitudinal strain of the creasing operation by pressure against the said end edge of the blank.

v FRANK H. STOLP. 

